báo cáo hóa học: " Interleukin-1 receptor 1 knockout has no effect on amyloid deposition in Tg2576 mice and does not alter efficacy following Aβ immunotherapy" pot

BioMed Central
Page 1 of 13
(page number not for citation purposes)
Journal of Neuroinflammation
Open Access
Research
Interleukin-1 receptor 1 knockout has no effect on amyloid
deposition in Tg2576 mice and does not alter efficacy following Aβ
immunotherapy
Pritam Das*, Lisa A Smithson, Robert W Price, Vallie M Holloway,
Yona Levites, Paramita Chakrabarty and Todd E Golde*
Address: Department of Neurosciences, Mayo Clinic College of Medicine, 4500 San Pablo Road, Jacksonville, FL 32224, USA
Email: Pritam Das* - ; Lisa A Smithson - ; Robert W Price - ;
Vallie M Holloway - ; Yona Levites - ;
Paramita Chakrabarty - ; Todd E Golde* -
* Corresponding authors
Abstract
Background: Microglial activation has been proposed to facilitate clearance of amyloid β protein
(Aβ) from the brain following Aβ immunotherapy in amyloid precursor protein (APP) transgenic
mice. Interleukin-1 receptor 1 knockout (IL-1 R1-/-) mice are reported to exhibit blunted
inflammatory responses to injury. To further define the role of IL-1-mediated inflammatory
responses and microglial activation in this paradigm, we examined the efficacy of passive Aβ
immunotherapy in Tg2576 mice crossed into the IL-1 R1-/- background. In addition, we examined
if loss of IL-1 R1-/- modifies Aβ deposition in the absence of additional manipulations.
Methods: We passively immunized Tg2576 mice crossed into the IL-1 R1-/- background (APP/IL-
1 R1-/- mice) with an anti-Aβ1-16 mAb (mAb9, IgG2a) that we previously showed could attenuate
Aβ deposition in Tg2576 mice. We also examined whether the IL-1 R1 knockout background
modifies Aβ deposition in untreated mice. Biochemical and immunohistochemical Aβ loads and
microglial activation was assessed.
Results: Passive immunization with anti-Aβ mAb was effective in reducing plaque load in APP/IL-
1 R1-/- mice when the immunization was started prior to significant plaque deposition. Similar to

previous studies, immunization was not effective in older APP/IL-1 R1-/- mice or IL-1 R1 sufficient
wild type Tg2576 mice. Our analysis of Aβ deposition in the untreated APP/IL-1 R1-/- mice did not
show differences on biochemical Aβ loads during normal aging of these mice compared to IL-1 R1
sufficient wild type Tg2576 mice.
Conclusion: We find no evidence that the lack of the IL-1 R1 receptor influences either Aβ
deposition or the efficacy of passive immunotherapy. Such results are consistent with other studies
in Tg2576 mice that suggest microglial activation may not be required for efficacy in passive
immunization approaches.
Published: 26 July 2006
Journal of Neuroinflammation 2006, 3:17 doi:10.1186/1742-2094-3-17
Received: 13 March 2006
Accepted: 26 July 2006
This article is available from: />© 2006 Das et al; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( />),
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Journal of Neuroinflammation 2006, 3:17 />Page 2 of 13
(page number not for citation purposes)
Background
Direct immunization with aggregated amyloid β protein
(Aβ) and passive immunization with anti-Aβ antibodies
(Abs) reduce plaque burden in Alzheimer's disease (AD)
mouse models and improve cognitive deficits present in
those models [1-5]. Although no adverse effects of immu-
nization were noted in earlier studies, more recent data in
mice indicate that there is the potential of exacerbation of
cerebral-amyloid angiopathy (CAA) associated microhe-
mmorhages in certain mouse strains following passive
immunization with certain anti-Aβ antibodies [6-8]. An
active immunization trial in humans was initiated using
fibrillar Aβ42+QS-21 adjuvant (AN-1792) but was halted

due to a meningio-encephalitic presentation in ~6% of
individuals [9-11]. Reports of individuals enrolled in the
trial suggest that those subjects who developed modest
anti-plaque antibody (Ab) titers did show some clinical
benefit relative to subjects that did not develop detectable
titers [9,11,12]. A small phase II study of AD patients
administered human IVIG containing anti-Aβ Abs
showed slight improvement in ADAScog following
administration; however the clinical effect was modest
and only a few subjects were evaluated [13].
Given the pre-clinical data, hints of efficacy in humans,
and the lack of disease-modifying therapies for AD, Aβ
immunotherapy or derivative approaches are still worthy
of pursuing. However, the mechanism or mechanisms
through which Aβ immunotherapy works remain enig-
matic [14,15]. The amount of Aβ deposited when immu-
nization is initiated, the AD mouse model used, and the
properties of the anti-Aβ antibodies used, all affect the
outcome [1,2,16-18]. One of the debates with respect to
mechanism centers on peripheral versus a central action
of the antibody [3,19,20]. There is evidence to support
both mechanisms, and it will be a very difficult issue to
definitively address this through additional experimenta-
tion. Another debate is in regard to the role of microglia
activation. Several groups report transient or stable
enhancements of microglia activation associated with Aβ
removal; others do not [1,21-23]. In postmortem human
tissue from AD patients who had received the AN-1792
vaccine, Aβ-laden microglia were noted in areas where Aβ
clearance is hypothesized to have occurred [24]. Thus,

microglial activation has been proposed to facilitate
removal of Aβ from the brain following vaccination.
The IL-1 superfamily (including IL-1β, IL-1α and IL-18) is
a group of cytokines that exhibit a large number of biolog-
ical responses [25]. Interleukin-1β is a key mediator of
host response to infections and a primary cause of inflam-
mation [25]. In vivo, IL-1β is elevated during infections
and in several chronic inflammatory diseases such as
arthritis, scleroderma, systemic lupus erythematosus, vas-
culitis, sepsis, septic shock, and atherosclerotic lesions as
well as in brains of AD patients [25]. As least two IL-1
receptors (IL-1R) have been identified: type I and type II
receptors (IL-RI and IL-RII) [26]. IL-1β binds IL-1RI and
upon IL-1 binding, IL-1RI recruits the accessory protein
IL-1R-AcP, and initiates a stimulatory signal transduction
cascade [26]. IL-1RII acts as a decoy receptor and com-
petes with IL-1RI to down-modulate IL-1 activity [27]. In
AD and Down's syndrome, IL-1β production is increased
in microglial cells in the vicinity of amyloid plaques
[28,29]. Initial studies examining the association of poly-
morphisms in the IL-1 and IL-1 receptor genes showed
positive association of certain alleles with AD risk [30-34].
However, like many AD genetic association studies, sub-
sequent studies failed to confirm the initial association.
Meta-analyses of all studies on IL-1α and β linkage show
no evidence for association of these loci with AD http://
www.alzforum.org/res/com/gen/alzgene/. A recent report
shows that activation of microglia with secreted APP
(sAPPα) results in a dose-dependent increase in secreted
IL-1β [35]. Similarly, cortical neurons treated with IL-1β

showed a dose-dependent increase in sAPPα secretion,
elevated levels of α-synuclein and phosphorylated tau
[35]. In APP transgenic mice, IL-1 reactivity and other
inflammatory markers are increased in microglial cells
surrounding amyloid deposits during various stages of
amyloid deposition in these mice [36,37]. Another mem-
ber of the IL-1 superfamily, IL-1 receptor antagonist (IL-
1Ra) [38], is also synthesized and released in parallel to
IL-1β, IL-1α, and IL-18. IL-1Ra binds to IL-1RI and blocks
IL-1 dependent signal transduction, thus functioning as
an endogenous, IL-1 selective inhibitor of inflammation
[38]. Interestingly, IL-1Ra knockout mice show enhanced
microglial activation and neuronal damage following
intracerebroventricular infusion of human Aβ [39]. Col-
lectively, these data suggest that IL-1 is a key mediator of
microgliosis and subsequent inflammatory responses fol-
lowing Aβ deposition as well as in the production of sub-
strates necessary for neuropathological changes seen in
AD.
To gain additional insight into the role of IL-1 signaling
on microglial activation, on IL-1-mediated inflammatory
responses following Aβ vaccination, and on Aβ deposi-
tion during normal aging, we used interleukin-1 receptor
1-knockout (IL-1 R1-/-) mice [40-42] that were crossed to
APP Tg2576 transgenic mice (APP/IL-1 R1-/-). The IL-1
R1-/- mice lack the type 1 interleukin-1 receptor, but
develop normally. Moreover, with a few exceptions, these
mice are normal, showing alterations in IL-1-mediated
immune response to certain stimuli. Following penetrat-
ing brain injury in IL1-R1-/- mice, fewer amoeboid micro-

glia/macrophages are present near the sites of injury,
astrogliosis is mildly abrogated and cyclooxygenase-2
(Cox-2) and IL-6 expression are reduced [42]. In another
report, IL-1 R1-/- mice failed to respond to IL-1 in several
Journal of Neuroinflammation 2006, 3:17 />Page 3 of 13
(page number not for citation purposes)
assays, including IL-1-induced IL-6 and E-selectin expres-
sion, and IL-1-induced fever and acute-phase responses to
turpentine [41]. These data in IL-1 R1-/- mice demonstrate
that IL-1 R1 is critical for most IL-1-mediated signaling
events tested. We performed passive immunization with
an anti-Aβ mAb in Tg2576 mice crossed into the IL-1 R1-
/- background (APP/IL-1 R1-/-), and determined whether
microglial activation and consequent inflammatory
responses are necessary for Aβ reduction. These studies
show that passive immunization with anti-Aβ mAb is
effective in reducing plaque load in APP/IL-1 R1-/- mice
when the immunization is started prior to significant
plaque deposition and thus support our general hypothe-
sis that microglial activation may not be required for effi-
cacy of immunization in Tg2576 mice.
Methods
Mice breeding strategy
Tg2576 [43] were bred into the IL-1 R1-knockout back-
ground (B6.129S7-Il1r1tm1Imx, Jackson Laboratories) as
follows; male Tg2576 (C57BL/6.SJL) were initially
crossed with IL-1 R1-/- females (B6.129S7). We then back-
crossed the F1 Tg2576 × IL-1R1+/- males with female IL-1
R1-/ These crosses generated the F2 Tg2576 × IL-1R1-/-
mice (APP/IL-1 R1-/-) and Tg2576 × IL-1R1+/- littermates

(APP/IL-1 R1+/-), which were used in all experiments. All
animal experimental procedures were performed accord-
ing to Mayo Clinic Institutional Animal Care and Use
Committee guidelines. All animals were housed three to
five to a cage and maintained on ad libitum and water with
a 12 h light/dark cycle.
Passive immunizations
Groups of APP/IL-1 R1-/- mice and APP/IL-1 R1+/- litter-
mates (males and females, 6-month-old or 12-month-
old, n = 3-5/group) were immunized intraperitoneally
(i.p.) with 500 μg of mAb9 (Aβ1-16 specific, IgG2a) in
saline once every 2 weeks for 3 months. Control mice
received 500 μg of purified mouse IgG in saline.
ELISA analysis of extracted A
β
At sacrifice, the brains of mice were divided by midsagittal
dissection, and 1 hemibrain was used for biochemical
analysis as described previously [18]. Briefly, each hemi-
brain (150 mg/ml wet wt) was extracted in 2% SDS with
protease inhibitors using a polytron and centrifuged at
100,000 g for 1 hour at 4°C. Following centrifugation, the
supernatant was collected, which represented the SDS-sol-
uble fraction. The resultant pellet was then extracted in
70% FA, using a probe sonicator, centrifuged at 100,000 g
for 1 hour at 4°C, and the supernatant collected (the FA
fraction). Extracted Aβ was then measured using a sand-
wich ELISA system as described before [18]; Aβ 42-capture
with mAb 2.1.3 (mAb40.2,) and detection with HRP-con-
jugated mAb Ab9 (human Aβ1-16 specific); Aβ40- capture
with mAb Ab9 and detection with HRP-conjugated mAb

13.1.1 (mAβ40.1)
Immunohistology
Hemibrains of mice were fixed in 4% paraformaldehyde
in 0.1 M PBS (pH 7.6) and then stained for Aβ plaques as
described previously [18]. Paraffin sections (5 μm) were
pretreated with 80% FA for 5 minutes, boiled in water
using a rice steam cooker, washed, and immersed in 0.3%
H2O2 for 30 minutes to block intrinsic peroxidase activ-
ity. They were then incubated with 2% normal goat serum
in PBS for 1 hour, with 33.1.1 (Aβ1-16 mAb) at 1 μg/ml
dilution overnight, and then with HRP-conjugated goat
anti-mouse secondary mAb (1:500 dilution; Amersham
Biosciences) for 1 hour. Sections were washed in PBS, and
immunoreactivity was visualized by 3,3'-diaminobenzi-
dine tetrahydrochloride (DAB) according to the manufac-
turer's specifications (ABC system; Vector Laboratories).
Adjacent sections were stained with 4% thioflavin-S for 10
minutes. Free-floating 4% paraformaldehyde-fixed, fro-
zen tissue sections (30 μM) were stained for the presence
of activated microglia with rat anti-mouse CD45 (1:3000;
Serotec, Oxford, UK), followed by detection with anti-rat-
HRP (ABC system, Vector Labs), and then counterstained
with Thio-S as described previously [23]. Four percent
paraformaldehyde-fixed, paraffin-embedded sections
were stained for activated microglia using anti-Iba1
(1:3000; Wako Chemicals) and for activated astrocytes
using anti-GFAP (1:1000, Chemicon).
Quantitation of amyloid plaque burden
Computer-assisted quantification of Aβ plaques was per-
formed using he MetaMorph 6.1 software (Universal

Imaging Corp, Downington, PA). Serial coronal sections
stained as above were captured, and the threshold for
plaque staining was determined and kept constant
throughout the analysis. For analysis of plaque burdens in
the passive immunization experiments, immunostained
plaques were quantified (proportional area of plaque bur-
den) in the neocortex of the same plane of section for each
mouse (~10 sections per mouse). All of the above analyses
were performed in a blinded fashion.
Statistical analysis
One-way ANOVA followed by Dunnett's multiple com-
parison tests were performed using the scientific statistic
software Prism (version 4; GraphPad).
Results
Interleukin-1 receptor 1 knockout has no effect on A
β

loads in Tg2576 mice
To investigate whether the lack of IL-1 R1 had any effect
on Aβ deposition, we analyzed biochemically extractable
Aβ levels and immuno-reactive plaque burdens in Tg2576
mice crossed to IL-1 R1-/- mice (APP/IL-1 R1-/-). APP/IL-
Journal of Neuroinflammation 2006, 3:17 />Page 4 of 13
(page number not for citation purposes)
1 R1-/- mice were compared to APP/IL-1 R1+/-
hemizygous littermates to control for differences in the
background genes, as a result of our breeding strategy
(Tg2576 in F1 C57BL/6.SJL background and IL1-R1-/-
mice in B6.129S7 background). Thus, APP/IL-1 R1-/- mice
and APP/IL-1 R1+/- hemizygous littermates generated are

in similar mixed C57BL/6.SJL and C57BL/6.129S7 back-
grounds. We have also compared the crossed mice to wild
type Tg2576 mice (referred to as IL-1 R1+/+) in various
measurements, though these mice are in a different back-
ground (F2 C57BL/6.SJL).
Groups of mice at various ages (6 months, 9 months and
15 months of age) were killed and the levels of both SDS-
soluble (SDS) and SDS-insoluble FA-extractable fractions
of Aβ40 and Aβ42 were analyzed by ELISA. As shown in
Figure 1, there were no significant differences in the
amounts of extractable Aβ in all three ages groups tested
when we compared Aβ levels in APP/IL-1 R1-/-, APP/IL-1
R1+/- littermates and wild type Tg2576 mice: SDS Aβ42
(Figure 1A), SDS Aβ40 (Figure 1B), FA Aβ42 (Figure 1C),
and FA Aβ40 (Figure 1D). To further examine whether
there were alterations in deposited Aβ plaques in these
Aβ levels in APP/IL-1 R1-/- mice, APP/IL-1 R1+/-littermates and wild type Tg2576 mice at 6 months, 9 months and 15 months of ageFigure 1
Aβ levels in APP/IL-1 R1-/- mice, APP/IL-1 R1+/-littermates and wild type Tg2576 mice at 6 months, 9 months and 15 months
of age. Groups of mice were killed at the indicated time points and both SDS-soluble (SDS) and SDS-insoluble, formic acid
extractable (FA) fractions of Aβ40 and Aβ42 were measured by capture ELISA.
0
50
100
APP/IL-1R1 -/-
APP/IL-1R1+/-
6M
Age of mice (Months)
150
350
550

15M
9M
Tg2576 (IL-1R1+/+)
SDS 42 (pM/g)
0
100
200
APP/IL-1R1 -/-
APP/IL-1R1+/-
6M
Age of mice (Months)
500
1500
2500
3500
15M9M
Tg2576 (IL-1R1+/+)
SDS 40 (pM/g)
0
100
200
APP/IL-1R1 -/-
APP/IL-1R1+/-
6M
Age of mice (Months)
500
1500
2500
3500
15M

9M
Tg2576 (IL-1R1+/+)
FA42 (pM/g)
0
250
500
APP/IL-1R1 -/-
APP/IL-1R1+/-
6M
Age of mice (Months)
5000
15000
25000
15M
9M
Tg2576 (IL-1R1+/+)
FA40 (pM/g)
A
B
C
D
Journal of Neuroinflammation 2006, 3:17 />Page 5 of 13
(page number not for citation purposes)
mice, coronal sections of each mouse hemibrain were
analyzed for changes in immunostained Aβ plaque loads.
Quantitative image analysis of amyloid plaque burden in
all age groups revealed no significant differences (data not
shown). However, in 2 of 7 mice analyzed in the 15-
month-old APP/IL-1 R1-/-, there was atypical Aβ plaque
staining. An appreciable increase in diffuse immuno-reac-

tive Aβ plaques (Figure 2B) in the neocortex of these 2
mice was noted when compared to the 15-month-old
APP/IL-1 R1+/- littermates (Figure 2A) or wild type
Tg2576 mice (Figure 2C), which deposit more dense-
cored Aβ plaques at this age.
Passive immunotherapy is effective in young APP/IL-1 R1-/
- mice
To examine the effects of microglial activation on Aβ
immunotherapy, we examined the effects of passive
immunization with an anti-Aβ monoclonal antibody
(mAb9) in APP/IL-1 R1-/-mice. Two experimental para-
digms were used: i) a prevention study, in which passive
immunization was performed in 6-month-old mice,
which at this time have minimal Aβ deposition, and ii) a
therapeutic study, in which immunotherapy was per-
formed using 12-month-old mice, which have moderate
levels of preexisting Aβ deposits. Both groups of mice were
treated for 3 months then killed; and biochemical and
immunohistochemical methods were used to analyze the
effect of immunotherapy. Following passive immuniza-
tion with mAb9 initiated in the 6-month-old mice (pre-
vention study), Aβ levels were significantly attenuated in
both the APP/IL-1 R1-/- and APP/IL-1 R1+/- littermates
(Figure 3). Both the SDS-extractable Aβ levels (>50%
reduction in SDS Aβ; Figure 3A and 3B) and formic acid-
(FA-) solubilized, SDS-insoluble material (>50% reduc-
tion in FA Aβ; Figure 3A and 3B) were reduced in these
mice. Quantitative image analysis of immunostained sec-
tions also showed a significant decrease in Aβ deposition
in both groups (as measured by plaque numbers per field,

Figure 3E). In contrast, passive immunization with mAb9,
initiated in the 12-month-old mice (therapeutic study)
had no significant effect on biochemically extracted Aβ
levels (Figure 3C and 3D) or immuno-reactive Aβ; plaque
loads (Figure 3F), in the both the APP/IL-1 R1-/- or APP/
IL-1 R1+/- littermates.
Interleukin-1 receptor 1 knockout has no effect on
microglial reactivity surrounding A
β
plaques
To access whether the IL-1 R1-/- phenotype affected the
state of microglial activation, and astrocyte reactivity, par-
ticularly, glial reactivity surrounding amyloid plaques, we
compared the intensity of staining of microglia using anti-
bodies against CD45, a marker for activated microglia that
has been shown to be present on activated microglia sur-
rounding amyloid plaques in APP transgenic mice [44]
and Iba1, the ionized calcium-binding adaptor molecule
1, which is expressed selectively in activated microglia/
macrophages [45]. For CD45 staining, coronal sections
from both unmanipulated APP/IL-1 R1-/-, APP/IL-1 R1+/
Representative pictures of immunostained Aβ plaques (stained with anti-Aβ antibody) in the neocortex of (A) a 15-month-old APP/IL-1 R1+/- mouse; (B) a 15-month-old APP/IL-1 R1-/- mouse; and (C) a 15-month-old wild type Tg2576 mice (IL_1 R1+/+)Figure 2
Representative pictures of immunostained Aβ plaques
(stained with anti-Aβ antibody) in the neocortex of (A) a 15-
month-old APP/IL-1 R1+/- mouse; (B) a 15-month-old APP/
IL-1 R1-/- mouse; and (C) a 15-month-old wild type Tg2576
mice (IL_1 R1+/+). (A, B, C, magnification = 100×, insert
shows enlargement of Aβ plaques).
Journal of Neuroinflammation 2006, 3:17 />Page 6 of 13
(page number not for citation purposes)

A and B. Aβ levels were significantly reduced following mAb9 immunizations initiated in 6-month-old APP/IL-1 R1-/- mice as well as APP/IL-1 R1+/- mice (n = 3/group)Figure 3
A and B. Aβ levels were significantly reduced following mAb9 immunizations initiated in 6-month-old APP/IL-1 R1-/- mice as
well as APP/IL-1 R1+/- mice (n = 3/group). C and D. Aβ levels were not significantly altered following mAb9 immunizations
initiated in 12-month-old APP/IL-1 R1-/- mice and APP/IL-1 R1+/- mice (n = 3–5/group). Mice were killed after immunization
with 500 μg of mAb9 every other week for 3 months, and both SDS-soluble (SDS) and SDS-insoluble, formic acid extractable
(FA) fractions of Aβ40 and Aβ42 were measured by capture ELISA. E and F. Quantitative image analysis of amyloid plaque
burden in the neocortex of mAb9 immunizations initiated in 6-month-old APP/IL-1 R1-/- mice (E) and mAb9 immunizations
initiated in 12-month-old APP/IL-1 R1-/- mice (F). (*, ** P < 0.05 t-test)
Co
n
trol (I
L
-1R
1
-/-
)
mAb Im (IL-1R1-/-)
Con
t
r
o
l(IL
-
1R1
+
/-)
m
Ab I
m
(IL-1R1

+
/
-
)
0
25
50
75
100
125
150
175
FA42
SDS42
A
*
**
**
6-month-old group
A
β
β
β
β
42 (pM/gm)
C
o
ntrol
(
IL-1R1-/-)

mAb Im (IL-1R1-/-)
Co
n
t
rol
(
IL-1
R1+/-
)
m
Ab I
m
(IL-
1
R1
+
/-
)
0
1000
2000
3000
4000
FA42
SDS42
C
12-month-old group
A
β
β

β
β
42 (pM/gm)
Control (
I
L-
1
R1-/-)
mA
b
Im (IL-1R1-/-)
Control (IL-1R1+/-)
mAb Im (IL-1R1+/-)
0
100
200
300
400
500
FA40
SDS40
B
*
**
*
**
6-month-old group
A
β
β

β
β
40 (pM/gm)
Control (IL-1R
1
-/-)
mAb Im (IL
-
1R1-
/
-)
Co
ntr
o
l
(
I
L
-1R1
+/
-
)
mAb Im
(
IL
-
1R
1
+
/

-)
0
5000
10000
15000
20000
25000
FA40
SDS40
D
12-month-old group
A
β
β
β
β
40 (pM/gm)
Control (IL-1R
1
-/-)
mAb
Im (IL
-1R
1
-/
-)
C
ontrol
(I
L-1

R
1+/-)
m
A
b
Im
(I
L-
1R
1
+/-)
0
2
4
6
*
*
E
6-month-old group
Plaque number per field
C
o
n
trol (
I
L-
1
R
1
-

/-
)
m
A
bIm(I
L
-1
R
1
-
/-)
C
o
n
trol (IL-
1
R
1
+/-
)
m
Ab
Im
(IL
-
1
R
1
+/-)
0.00

0.25
0.50
0.75
1.00
*
*
F
12-month-old group
Immunoreactive Plaque Burden
(proportional area)
Journal of Neuroinflammation 2006, 3:17 />Page 7 of 13
(page number not for citation purposes)
- littermates and wild type Tg2576 mice (IL-1 R1 +/+) at 9-
months and 15-months of age were used for staining. As
shown in Figure 4, there were abundant numbers of CD45
immuno-reactive microglia present, surrounding Aβ
plaques from the 9-month-old APP/IL-1 R1-/- (Figure
4A), APP/IL-1 R1+/- littermates (Figure 4C) and wild type
Tg2576 mice (Figure 4E) with no obvious differences in
the CD45 reactivity in these activated microglial cells.
Greater numbers of immuno-reactive microglia were
present surrounding plaques in the 15-month-old mice,
but again, there were no discernable differences in the
density/CD45 reactivity in these microglial when we com-
pared sections from the 15-month-old APP/IL-1 R1-/-
(Figure 4B) vs. 15-month-old APP/IL-1 R1+/- littermates
(Figure 4D) or wild type Tg2576 mice (Figure 4F). Similar
results were seen when we compared the CD45 reactivity
of microglia in mice that were passively immunized with
mAb9 vs. controls, i.e., there were no differences in micro-

glial reactivity using CD45 staining comparing immu-
nized mice vs. controls in both groups (data not shown).
For anti-Iba1 antibody staining, we compared coronal sec-
tions from unmanipulated APP/IL-1 R1-/-, APP/IL-1 R1+/
- littermates and wild type Tg2576 mice (IL-1R1+/+) at 9
months and 15 months of age. As shown in Figure 5, anti-
Iba1 staining was readily detected in microglia surround-
ing Aβ plaques in all three groups of mice tested compar-
ing both 9-month-old and 15-month-old mice (Figure 5).
Similar to CD45 staining, there were no discernable differ-
ences in the Iba1 reactivity in microglial cells comparing
the APP/IL-1 R1-/-, APP/IL-1 R1+/- littermates and wild
type Tg2576 mice (IL-1R1+/+) mice. For staining of acti-
vated astrocytes, we used an anti-GFAP antibody and
compared immunoreactivity using coronal sections from
unmanipulated APP/IL-1 R1-/-, APP/IL-1 R1+/- litterma-
tes and wild type Tg2576 mice (IL-1R1+/+) at 9 months
and 15 months of age as before. As shown in Figure 6,
there was robust anti-GFAP reactivity on activated astro-
cytes surrounding Aβ plaques in all three groups of mice
tested (Figure 6). Again, similar to the microglial staining
pattern, there were no discernable differences in the GFAP
reactivity on astrocytes in all three groups of mice tested.
Discussion
Despite multiple studies of anti-Aβ immunotherapy in
mice, there is still no consensus on how anti-Aβ immuno-
therapy works [14,15], particularly as it relates to the role
of microglial activation. It was originally proposed that Aβ
immunization triggers phagocytosis of antibody-bound
Aβ immune complexes via microglial FcR. After immuni-

zation, increased number of microglial cells stained with
anti-Aβ antibodies were observed [1]. Indeed, using an ex
vivo strategy, it was shown that anti-Aβ antibodies induce
phagocytosis of Aβ plaques [2]. Importantly, Fab frag-
ments of these antibodies fail to induce Aβ phagocytosis,
suggesting that the enhanced uptake is attributable to FcR
[2]. Subsequent studies have shown that at least in
Tg2576 APP mice, a role for enhanced phagocytosis of
mAb:Aβ complexes via the FcR can largely be ruled out,
since Aβ1-42 immunization in Tg2576 × FcRγ-/- crossed
mice was effective in reducing Aβ loads [23]. Additional
studies now show that an intact mAb (and therefore FCR
interactions) is not required for efficacy; since Fab frag-
ments [46] and scFv fragments (Levites and Golde,
unpublished observation) are efficacious in immuno-
therapy. Several groups have reported that following Aβ
immunotherapy, there are transient or stable enhance-
ments of microglial activation associated with Aβ
removal; whereas others do not find this [1,21-23]. Fur-
thermore, in humans receiving the AN-1792 vaccine, Aβ-
laden microglia have been noted in postmortem studies
[24]. Although antibody and microglial Fc receptor-medi-
ated interactions have been suggested to activate micro-
glia following vaccinations, other inflammatory
consequences may play a role in this paradigm. Based on
published reports, it has been suggested that clearance of
amyloid deposits in patients enrolled in the AN-1792 trial
may have been due to an adverse inflammatory response
to the vaccine rather than due to the anti-Aβ antibodies
[47]. This proposition may be supported by some recent

reports, wherein induction of experimental autoimmune
encephalitis (EAE) and nasal vaccination with glatiramer
acetate reportedly decrease amyloid plaques in APP trans-
genic mice [48]. Another report by the same group shows
that, in mice over expressing IFN-gamma in the CNS,
amyloid vaccination lead to meningoencephalitis and T
cell-dependent clearance of amyloid plaques from the
brain [49]. Both of these reports provide evidence that
peripheral inflammatory responses and CNS autoreactive
T cells may play a role in vaccination-induced clearance of
plaques. Furthermore, some recent reports have indicated
that inflammatory insults, either by injecting LPS directly
into the brain [44,50] or overexpression of TGF-β in the
CNS [51], can result in reductions of amyloid deposits.
Enhanced microglial activation was noted in both of these
reports and is suggested to contribute to the clearance of
amyloid deposits.
In this report, we sought to determine the role of IL-1-
mediated microglial activation on IL-1-mediated inflam-
matory responses following Aβ vaccination and on Aβ
deposition during normal aging using interleukin-1
receptor 1-knockout (IL-1 R1-/-) mice [40-42] that were
crossed to APP Tg2576 transgenic mice (APP/IL-1 R1-/-).
We first tested the efficacy of Aβ immunization in APP/IL-
1 R1-/- mice. Our results show that passive immunization
with an anti-Aβ mAb is effective in reducing plaque loads
both in APP/IL-1 R1-/- mice and APP/IL-1 R1+/- litterma-
tes, when immunization is started prior to significant
plaque deposition. However, as we have seen previously,
immunization was not efficacious in mice that have pre-

Journal of Neuroinflammation 2006, 3:17 />Page 8 of 13
(page number not for citation purposes)
Representative pictures of Thioflavin-S-stained Aβ plaques (lightly stained areas) decorated with ramified microglia immunos-tained with anti-mouse CD45 (black stain) in the neo cortex of untreated (A) 9-month-old APP/IL-1 R1-/- and (B) 15-month-old APP/IL-1 R1-/-; (C) 9-month-old APP/IL-1 R1+/- and (D) 15-month-old APP/IL-1 R1+/-; (E) 9-month-old wild type Tg2576 mice (IL-1 R1+/+) and (F) 15-month-old wild type Tg2576 mice (IL-1 R1+/+)Figure 4
Representative pictures of Thioflavin-S-stained Aβ plaques (lightly stained areas) decorated with ramified microglia immunos-
tained with anti-mouse CD45 (black stain) in the neo cortex of untreated (A) 9-month-old APP/IL-1 R1-/- and (B) 15-month-
old APP/IL-1 R1-/-; (C) 9-month-old APP/IL-1 R1+/- and (D) 15-month-old APP/IL-1 R1+/-; (E) 9-month-old wild type Tg2576
mice (IL-1 R1+/+) and (F) 15-month-old wild type Tg2576 mice (IL-1 R1+/+). (A, B, C, D, E, F magnification = 400×).
Journal of Neuroinflammation 2006, 3:17 />Page 9 of 13
(page number not for citation purposes)
existing Aβ loads [17,18,52]. Thus, these results support
our general hypothesis that microglial activation may not
be required for efficacy of immunization in Tg2576 mice.
The lack of IL-1 R1 (in -/- mice) did not significantly alter
Aβ deposition in untreated mice. There were no signifi-
cant differences in total extractable Aβ levels or overall his-
tochemical loads, at any time, between the APP/IL-1 R1-/
- mice and APP/IL-1 R1+/- littermates compared to wild
Representative pictures of Thioflavin-S-stained Aβ plaques (lightly stained areas) decorated with microglia immunostained with anti-Iba1 (brown stain) in the neocortex of untreated (A) 9-month-old APP/IL-1 R1-/- and (B) 15-month-old APP/IL-1 R1-/-; (C) 9-month-old APP/IL-1 R1+/- and (D) 15-month-old APP/IL-1 R1+/-; (E) 9-month-old wild type Tg2576 mice (IL-1 R1+/+) and (F) 15-month-old wild type Tg2576 mice (IL-1 R1+/+)Figure 5
Representative pictures of Thioflavin-S-stained Aβ plaques (lightly stained areas) decorated with microglia immunostained with
anti-Iba1 (brown stain) in the neocortex of untreated (A) 9-month-old APP/IL-1 R1-/- and (B) 15-month-old APP/IL-1 R1-/-;
(C) 9-month-old APP/IL-1 R1+/- and (D) 15-month-old APP/IL-1 R1+/-; (E) 9-month-old wild type Tg2576 mice (IL-1 R1+/+)
and (F) 15-month-old wild type Tg2576 mice (IL-1 R1+/+). (A, B, C, D, E, F magnification = 400×).
Journal of Neuroinflammation 2006, 3:17 />Page 10 of 13
(page number not for citation purposes)
type Tg2576 mice (IL-1 R1+/+). Curiously, in 2 of 7 15-
month-old APP/IL-1 R1-/- mice examined, an unusual
pattern of Aβ plaque staining was noted, with an abun-
dance of diffuse immuno-reactive Aβ plaques in the neo-
cortex of these mice. It is not clear at this time whether this
unusual pattern of diffuse Aβ deposits is due to the IL-1

Representative pictures of Thioflavin-S-stained Aβ plaques (lightly stained areas) decorated with activated astrocytes immunos-tained with anti-GFAP (brown stain) in the neocortex of untreated (A) 9-month-old APP/IL-1 R1-/- and (B) 15-month-old APP/IL-1 R1-/-; (C) 9-month-old APP/IL-1 R1+/- and (D) 15-month-old APP/IL-1 R1+/-; (E) 9-month-old wild type Tg2576 mice (IL-1 R1+/+) and (F) 15-month-old wild type Tg2576 mice (IL-1 R1+/+)Figure 6
Representative pictures of Thioflavin-S-stained Aβ plaques (lightly stained areas) decorated with activated astrocytes immunos-
tained with anti-GFAP (brown stain) in the neocortex of untreated (A) 9-month-old APP/IL-1 R1-/- and (B) 15-month-old
APP/IL-1 R1-/-; (C) 9-month-old APP/IL-1 R1+/- and (D) 15-month-old APP/IL-1 R1+/-; (E) 9-month-old wild type Tg2576
mice (IL-1 R1+/+) and (F) 15-month-old wild type Tg2576 mice (IL-1 R1+/+). (A, B, C, D, E, F magnification = 400×).
Journal of Neuroinflammation 2006, 3:17 />Page 11 of 13
(page number not for citation purposes)
R1-/- phenotype or some mouse background effect. We
then examined the effects of IL-1 R1 knockout on the state
of microglial activation and astrogliosis surrounding amy-
loid plaques deposits. For microglial staining, we used
two well characterized markers for microglial activation,
anti-mouse CD45 and Iba1, and for activated astrocytes
we used anti-GFAP staining. Our results show that there
were abundant numbers of CD45 and Iba1 immuno-reac-
tive microglia present, surrounding Aβ plaques in APP/IL-
1 R1-/-, APP/IL-1 R1+/- and wild type Tg2576 mice (IL-1
R1+/+), with no significant differences in the immuno-
reactivity of staining using these markers. Similarly,
robust GFAP staining was seen in all three groups of mice
analyzed, with no significant differences seen in the GFAP
immuno-reactivity comparing all three groups of mice.
Based on our immuno-staining analysis, we were not able
to ascertain whether abrogated IL-1 signaling in the IL-1
R1-/- mice blunted the inflammatory microglial response
or astrogliosis in the region of deposited Aβ plaques. Pre-
vious experiments in IL-1 R1-/- mice have shown abro-
gated IL-1-mediated responses following acute
inflammatory stimuli. In a stab wound model of injury in
the brain, IL1-R1-/- mice had fewer amoeboid microglia/

macrophages near the sites of injury, mildly abrogated
astrogliosis and reduced expression of cytokines induced
by IL-1 expression [42]. In another report, IL-1 R1-/- mice
had reduced IL-6 and E-selectin expression, and reduced
IL-1-induced fever and acute phase responses to turpen-
tine [41]. However, IL-1 R1-/- mice do not differ from
control mice in their responses to either a lethal challenge
with D-galactosamine plus LPS or high dose LPS [40],
indicating that IL-1 R1 signaling functions may not be
necessary for the response to LPS. Thus, it is possible that
the chronic nature of the microglial response during the
course of amyloid deposition may abrogate any acute or
subtle signaling events mediated through the IL-1 R1
receptor. Certainly, it is possible that other receptors for
IL-1 may compensate for the lack for IL-1 R1 in this situa-
tion. Besides the IL-1 R1 and IL-1 RII receptors, the
recently reported P2X7 receptor has also been implicated
to be a key player in IL-1 signaling [53] and could com-
pensate for the lack of IL-1R1 in IL-1 mediated signaling
events. Alternatively, the microglial response to deposited
Aβ may not require signaling through the IL-1 R1 recep-
tor. The LPS receptor (CD14) [54,55], the scavenger recep-
tor complex (CD36) [56] and toll-like receptors (TLR-2,
TLR-4) [57] can directly activate microglia in response to
amyloid deposition, possibly circumventing any IL-1 R1-
mediated signaling events in the IL-1 R1-/- mice.
Like our previous studies, these studies suggest that micro-
glial activation is not required for immunization to work
in Tg2576 mice, although this should not be viewed as
definitive. As indicated above, in the IL-1 R1-/- mice,

microgliosis and astrogliosis are mildly abrogated at best
and do not result in microglial paralysis. Thus experi-
ments using recently developed CD11b-HSVTK mice.
developed by Aguzzi and colleagues [58]. that enable
selective killing of microglia cells may provide more
definitive results.
Competing interests
The author(s) declare that they have no competing inter-
ests.
Authors' contributions
PD conceived the design of the study, performed experi-
mental analysis and data interpretation and prepared the
manuscript. LAS bred and maintained the IL-1 R1-/- mice,
performed immunizations, harvested tissues, performed
CD45 staining. RWP performed the Aβ ELISA. VMH per-
formed the image quantification and immunohistology.
YL performed Aβ plasma ELISA and aided in the prepara-
tion of the manuscript. PC performed Iba1 immunostain-
ing and APP western blotting. TEG conceived the design of
the study, aided in the preparation of the manuscript, and
provided critical analysis of the manuscript.
Acknowledgements
These studies were funded by the NIH/National Institute on Aging (grant
AG18454, to T.E. Golde). Additional resources from the Mayo Foundation,
made possible by a gift from Robert and Clarice Smith, were used to sup-
port the Tg2576 mouse colony that provided the mice used in these stud-
ies. P. Das and Y. Levites were supported by a Robert and Clarice Smith
Fellowship. We would like to thank Linda Rousseau, Virginia Phillips, and
Monica Castanedes-Casey for technical assistance.
References

1. Schenk D, Barbour R, Dunn W, Gordon G, Grajeda H, Guido T, Hu
K, Huang J, Johnson-Wood K, Khan K, Kholodenko D, Lee M, Liao Z,
Lieberburg I, Motter R, Mutter L, Soriano F, Shopp G, Vasquez N,
Vandevert C, Walker S, Wogulis M, Yednock T, Games D, Seubert P:
Immunization with amyloid-beta attenuates Alzheimer-dis-
ease-like pathology in the PDAPP mouse [see comments].
Nature 1999, 400(6740):173-177.
2. Bard F, Cannon C, Barbour R, Burke RL, Games D, Grajeda H, Guido
T, Hu K, Huang J, Johnson-Wood K, Khan K, Kholodenko D, Lee M,
Lieberburg I, Motter R, Nguyen M, Soriano F, Vasquez N, Weiss K,
Welch B, Seubert P, Schenk D, Yednock T: Peripherally adminis-
tered antibodies against amyloid beta-peptide enter the cen-
tral nervous system and reduce pathology in a mouse model
of Alzheimer disease. Nat Med 2000, 6(8):916-919.
3. DeMattos RB, Bales KR, Cummins DJ, Dodart JC, Paul SM, Holtzman
DM: Peripheral anti-A beta antibody alters CNS and plasma
A beta clearance and decreases brain A beta burden in a
mouse model of Alzheimer's disease. Proc Natl Acad Sci U S A
2001, 98(15):8850-8855.
4. Dodart JC, Bales KR, Gannon KS, Greene SJ, DeMattos RB, Mathis C,
DeLong CA, Wu S, Wu X, Holtzman DM, Paul SM: Immunization
reverses memory deficits without reducing brain Abeta bur-
den in Alzheimer's disease model. Nat Neurosci 2002,
5(5):452-457.
5. Brendza RP, Bacskai BJ, Cirrito JR, Simmons KA, Skoch JM, Klunk WE,
Mathis CA, Bales KR, Paul SM, Hyman BT, Holtzman DM: Anti-
Abeta antibody treatment promotes the rapid recovery of
amyloid-associated neuritic dystrophy in PDAPP transgenic
mice. J Clin Invest 2005, 115(2):428-433.
Journal of Neuroinflammation 2006, 3:17 />Page 12 of 13

(page number not for citation purposes)
6. Pfeifer M, Boncristiano S, Bondolfi L, Stalder A, Deller T, Staufenbiel
M, Mathews PM, Jucker M: Cerebral hemorrhage after passive
anti-Abeta immunotherapy. Science 2002, 298(5597):1379.
7. Racke MM, Boone LI, Hepburn DL, Parsadainian M, Bryan MT, Ness
DK, Piroozi KS, Jordan WH, Brown DD, Hoffman WP, Holtzman
DM, Bales KR, Gitter BD, May PC, Paul SM, DeMattos RB: Exacer-
bation of cerebral amyloid angiopathy-associated microhe-
morrhage in amyloid precursor protein transgenic mice by
immunotherapy is dependent on antibody recognition of
deposited forms of amyloid beta. J Neurosci 2005,
25(3):629-636.
8. Wilcock DM, Rojiani A, Rosenthal A, Subbarao S, Freeman MJ, Gor-
don MN, Morgan D: Passive immunotherapy against Abeta in
aged APP-transgenic mice reverses cognitive deficits and
depletes parenchymal amyloid deposits in spite of increased
vascular amyloid and microhemorrhage. J Neuroinflammation
2004, 1(1):24.
9. Gilman S, Koller M, Black RS, Jenkins L, Griffith SG, Fox NC, Eisner L,
Kirby L, Boada Rovira M, Forette F, Orgogozo JM: Clinical effects
of A{beta} immunization (AN1792) in patients with AD in an
interrupted trial. Neurology 2005.
10. Orgogozo JM, Gilman S, Dartigues JF, Laurent B, Puel M, Kirby LC,
Jouanny P, Dubois B, Eisner L, Flitman S, Michel BF, Boada M, Frank
A, Hock C: Subacute meningoencephalitis in a subset of
patients with AD after Abeta42 immunization. Neurology
2003, 61(1):46-54.
11. Nicoll JA, Wilkinson D, Holmes C, Steart P, Markham H, Weller RO:
Neuropathology of human Alzheimer disease after immuni-
zation with amyloid-beta peptide: a case report. Nat Med

2003, 9(4):448-452.
12. Hock C, Konietzko U, Streffer JR, Tracy J, Signorell A, Muller-Till-
manns B, Lemke U, Henke K, Moritz E, Garcia E, Wollmer MA,
Umbricht D, de Quervain DJ, Hofmann M, Maddalena A, Papassoti-
ropoulos A, Nitsch RM: Antibodies against beta-amyloid slow
cognitive decline in Alzheimer's disease. Neuron 2003,
38(4):547-554.
13. Dodel RC, Du Y, Depboylu C, Hampel H, Frolich L, Haag A, Hemme-
ter U, Paulsen S, Teipel SJ, Brettschneider S, Spottke A, Nolker C,
Moller HJ, Wei X, Farlow M, Sommer N, Oertel WH: Intravenous
immunoglobulins containing antibodies against beta-amy-
loid for the treatment of Alzheimer's disease. J Neurol Neuro-
surg Psychiatry 2004, 75(10):1472-1474.
14. Schenk D: Opinion: Amyloid-beta immunotherapy for Alzhe-
imer's disease: the end of the beginning. Nat Rev Neurosci 2002,
3(10):
824-828.
15. Das P, Golde TE: Open peer commentary regarding Abeta
immunization and CNS inflammation by Pasinetti et al. Neu-
robiol Aging 2002, 23(5):671.
16. Bard F, Barbour R, Cannon C, Carretto R, Fox M, Games D, Guido
T, Hoenow K, Hu K, Johnson-Wood K, Khan K, Kholodenko D, Lee
C, Lee M, Motter R, Nguyen M, Reed A, Schenk D, Tang P, Vasquez
N, Seubert P, Yednock T: Epitope and isotype specificities of
antibodies to beta -amyloid peptide for protection against
Alzheimer's disease-like neuropathology. Proc Natl Acad Sci U
S A 2003, 100(4):2023-2028.
17. Das P, Murphy MP, Younkin LH, Younkin SG, Golde TE: Reduced
effectiveness of Abeta1-42 immunization in APP transgenic
mice with significant amyloid deposition. Neurobiol Aging 2001,

22(5):721-727.
18. Levites Y, Das P, Price RW, Rochette MJ, Kostura LA, McGowan EM,
Murphy MP, Golde TE: Anti-Abeta42- and anti-Abeta40-specific
mAbs attenuate amyloid deposition in an Alzheimer disease
mouse model. J Clin Invest 2006, 116(1):193-201.
19. DeMattos RB, Bales KR, Cummins DJ, Paul SM, Holtzman DM: Brain
to plasma amyloid-beta efflux: a measure of brain amyloid
burden in a mouse model of Alzheimer's disease. Science
2002, 295(5563):2264-2267.
20. Oddo S, Caccamo A, Smith IF, Green KN, LaFerla FM: A dynamic
relationship between intracellular and extracellular pools of
Abeta. Am J Pathol 2006, 168(1):184-194.
21. Wilcock DM, DiCarlo G, Henderson D, Jackson J, Clarke K, Ugen KE,
Gordon MN, Morgan D: Intracranially administered anti-Abeta
antibodies reduce beta-amyloid deposition by mechanisms
both independent of and associated with microglial activa-
tion. J Neurosci 2003, 23(9):3745-3751.
22. Wilcock DM, Gordon MN, Ugen KE, Gottschall PE, DiCarlo G,
Dickey C, Boyett KW, Jantzen PT, Connor KE, Melachrino J, Hardy J,
Morgan D: Number of Abeta inoculations in APP+PS1 trans-
genic mice influences antibody titers, microglial activation,
and congophilic plaque levels. DNA Cell Biol 2001,
20(11):731-736.
23. Das P, Howard V, Loosbrock N, Dickson D, Murphy MP, Golde TE:
Amyloid-beta immunization effectively reduces amyloid
deposition in FcRgamma-/- knock-out mice.
J Neurosci 2003,
23(24):8532-8538.
24. Masliah E, Hansen L, Adame A, Crews L, Bard F, Lee C, Seubert P,
Games D, Kirby L, Schenk D: Abeta vaccination effects on

plaque pathology in the absence of encephalitis in Alzheimer
disease. Neurology 2005, 64(1):129-131.
25. Dinarello CA: The IL-1 family and inflammatory diseases. Clin
Exp Rheumatol 2002, 20(5 Suppl 27):S1-13.
26. Greenfeder SA, Nunes P, Kwee L, Labow M, Chizzonite RA, Ju G:
Molecular cloning and characterization of a second subunit
of the interleukin 1 receptor complex. J Biol Chem 1995,
270(23):13757-13765.
27. Colotta F, Re F, Muzio M, Bertini R, Polentarutti N, Sironi M, Giri JG,
Dower SK, Sims JE, Mantovani A: Interleukin-1 type II receptor:
a decoy target for IL-1 that is regulated by IL-4. Science 1993,
261(5120):472-475.
28. Sheng JG, Mrak RE, Griffin WS: Microglial interleukin-1 alpha
expression in brain regions in Alzheimer's disease: correla-
tion with neuritic plaque distribution. Neuropathol Appl Neuro-
biol 1995, 21(4):290-301.
29. Sheng JG, Ito K, Skinner RD, Mrak RE, Rovnaghi CR, Van Eldik LJ, Grif-
fin WS: In vivo and in vitro evidence supporting a role for the
inflammatory cytokine interleukin-1 as a driving force in
Alzheimer pathogenesis. Neurobiol Aging 1996, 17(5):761-766.
30. Mrak RE, Griffin WS: Potential inflammatory biomarkers in
Alzheimer's disease. J Alzheimers Dis 2005, 8(4):369-375.
31. Mrak RE, Griffin WS: Interleukin-1, neuroinflammation, and
Alzheimer's disease. Neurobiol Aging 2001, 22(6):903-908.
32. Nicoll JA, Mrak RE, Graham DI, Stewart J, Wilcock G, MacGowan S,
Esiri MM, Murray LS, Dewar D, Love S, Moss T, Griffin WS: Associ-
ation of interleukin-1 gene polymorphisms with Alzheimer's
disease [see comments]. Ann Neurol 2000, 47(3):365-368.
33. Du Y, Dodel RC, Eastwood BJ, Bales KR, Gao F, Lohmuller F, Muller
U, Kurz A, Zimmer R, Evans RM, Hake A, Gasser T, Oertel WH, Grif-

fin WS, Paul SM, Farlow MR: Association of an interleukin 1
alpha polymorphism with Alzheimer's disease [see com-
ments]. Neurology 2000, 55(4):480-483.
34. Griffin WS, Mrak RE: Interleukin-1 in the genesis and progres-
sion of and risk for development of neuronal degeneration in
Alzheimer's disease. J Leukoc Biol 2002, 72(2):233-238.
35. Griffin WS, Liu L, Li Y, Mrak RE, Barger SW: Interleukin-1 medi-
ates Alzheimer and Lewy body pathologies. J Neuroinflamma-
tion 2006, 3:5.
36. Benzing WC, Wujek JR, Ward EK, Shaffer D, Ashe KH, Younkin SG,
Brunden KR: Evidence for glial-mediated inflammation in
aged APP(SW) transgenic mice. Neurobiol Aging 1999,
20(6):581-589.
37. Mehlhorn G, Hollborn M, Schliebs R: Induction of cytokines in
glial cells surrounding cortical beta-amyloid plaques in trans-
genic Tg2576 mice with Alzheimer pathology. Int J Dev Neuro-
sci 2000, 18(4-5):423-431.
38. Dinarello CA: The role of the interleukin-1-receptor antago-
nist in blocking inflammation mediated by interleukin-1. N
Engl J Med 2000, 343(10):732-734.
39. Craft JM, Watterson DM, Hirsch E, Van Eldik LJ: Interleukin 1
receptor antagonist knockout mice show enhanced micro-
glial activation and neuronal damage induced by intracere-
broventricular infusion of human beta-amyloid. J
Neuroinflammation 2005, 2:15.
40. Glaccum MB, Stocking KL, Charrier K, Smith JL, Willis CR, Malisze-
wski C, Livingston DJ, Peschon JJ, Morrissey PJ: Phenotypic and
functional characterization of mice that lack the type I
receptor for IL-1. J Immunol 1997, 159(7):3364-3371.
41. Labow M, Shuster D, Zetterstrom M, Nunes P, Terry R, Cullinan EB,

Bartfai T, Solorzano C, Moldawer LL, Chizzonite R, McIntyre KW:
Absence of IL-1 signaling and reduced inflammatory
response in IL-1 type I receptor-deficient mice. J Immunol
1997, 159(5):2452-2461.
Publish with BioMed Central and every
scientist can read your work free of charge
"BioMed Central will be the most significant development for
disseminating the results of biomedical research in our lifetime."
Sir Paul Nurse, Cancer Research UK
Your research papers will be:
available free of charge to the entire biomedical community
peer reviewed and published immediately upon acceptance
cited in PubMed and archived on PubMed Central
yours — you keep the copyright
Submit your manuscript here:
/>BioMedcentral
Journal of Neuroinflammation 2006, 3:17 />Page 13 of 13
(page number not for citation purposes)
42. Basu A, Krady JK, O'Malley M, Styren SD, DeKosky ST, Levison SW:
The type 1 interleukin-1 receptor is essential for the efficient
activation of microglia and the induction of multiple proin-
flammatory mediators in response to brain injury. J Neurosci
2002, 22(14):6071-6082.
43. Hsiao K, Chapman P, Nilsen S, Eckman C, Harigaya Y, Younkin S, Yang
F, Cole G: Correlative memory deficits, Abeta elevation, and
amyloid plaques in transgenic mice [see comments]. Science
1996, 274(5284):99-102.
44. Morgan D, Gordon MN, Tan J, Wilcock D, Rojiani AM: Dynamic
complexity of the microglial activation response in trans-
genic models of amyloid deposition: implications for Alzhe-

imer therapeutics. J Neuropathol Exp Neurol 2005, 64(9):743-753.
45. Imai Y, Ibata I, Ito D, Ohsawa K, Kohsaka S: A novel gene iba1 in
the major histocompatibility complex class III region encod-
ing an EF hand protein expressed in a monocytic lineage. Bio-
chem Biophys Res Commun 1996, 224(3):855-862.
46. Bacskai BJ, Kajdasz ST, McLellan ME, Games D, Seubert P, Schenk D,
Hyman BT: Non-Fc-mediated mechanisms are involved in
clearance of amyloid-beta in vivo by immunotherapy. J Neu-
rosci 2002, 22(18):7873-7878.
47. Akiyama H, McGeer PL: Specificity of mechanisms for plaque
removal after A beta immunotherapy for Alzheimer disease.
Nat Med 2004, 10(2):117-8; author reply 118-9.
48. Frenkel D, Maron R, Burt DS, Weiner HL: Nasal vaccination with
a proteosome-based adjuvant and glatiramer acetate clears
beta-amyloid in a mouse model of Alzheimer disease. J Clin
Invest 2005, 115(9):2423-2433.
49. Monsonego A, Imitola J, Petrovic S, Zota V, Nemirovsky A, Baron R,
Fisher Y, Owens T, Weiner HL: Abeta-induced meningoen-
cephalitis is IFN-gamma-dependent and is associated with T
cell-dependent clearance of Abeta in a mouse model of
Alzheimer's disease. Proc Natl Acad Sci U S A 2006,
103(13):5048-5053.
50. DiCarlo G, Wilcock D, Henderson D, Gordon M, Morgan D: Intra-
hippocampal LPS injections reduce Abeta load in APP+PS1
transgenic mice. Neurobiol Aging 2001, 22(6):1007-1012.
51. Wyss-Coray T, Lin C, Yan F, Yu GQ, Rohde M, McConlogue L,
Masliah E, Mucke L: TGF-beta1 promotes microglial amyloid-
beta clearance and reduces plaque burden in transgenic
mice.
Nat Med 2001, 7(5):612-618.

52. Zhou J, Fonseca MI, Kayed R, Hernandez I, Webster SD, Yazan O,
Cribbs DH, Glabe CG, Tenner AJ: Novel Abeta peptide immuno-
gens modulate plaque pathology and inflammation in a
murine model of Alzheimer's disease. J Neuroinflammation 2005,
2:28.
53. Ferrari D, Pizzirani C, Adinolfi E, Lemoli RM, Curti A, Idzko M, Pan-
ther E, Di Virgilio F: The P2X7 receptor: a key player in IL-1
processing and release. J Immunol 2006, 176(7):3877-3883.
54. Liu Y, Walter S, Stagi M, Cherny D, Letiembre M, Schulz-Schaeffer W,
Heine H, Penke B, Neumann H, Fassbender K: LPS receptor
(CD14): a receptor for phagocytosis of Alzheimer's amyloid
peptide. Brain 2005, 128(Pt 8):1778-1789.
55. Fassbender K, Walter S, Kuhl S, Landmann R, Ishii K, Bertsch T, Stal-
der AK, Muehlhauser F, Liu Y, Ulmer AJ, Rivest S, Lentschat A, Gul-
bins E, Jucker M, Staufenbiel M, Brechtel K, Walter J, Multhaup G,
Penke B, Adachi Y, Hartmann T, Beyreuther K: The LPS receptor
(CD14) links innate immunity with Alzheimer's disease.
Faseb J 2004, 18(1):203-205.
56. Koenigsknecht J, Landreth G: Microglial phagocytosis of fibrillar
beta-amyloid through a beta1 integrin-dependent mecha-
nism. J Neurosci 2004, 24(44):9838-9846.
57. Chen K, Iribarren P, Hu J, Chen J, Gong W, Cho EH, Lockett S, Dun-
lop NM, Wang JM: Activation of Toll-like receptor 2 on micro-
glia promotes cell uptake of Alzheimer disease-associated
amyloid beta peptide. J Biol Chem 2006, 281(6):3651-3659.
58. Heppner FL, Greter M, Marino D, Falsig J, Raivich G, Hovelmeyer N,
Waisman A, Rulicke T, Prinz M, Priller J, Becher B, Aguzzi A: Exper-
imental autoimmune encephalomyelitis repressed by micro-
glial paralysis. Nat Med 2005, 11(2):146-152.